1. Field of the Invention
The present invention is related to a magnet-positioning device for a rotor and more particularly to the magnet-positioning device having assembling members adapted to combine a metal casing convenient with a rotor hub.
2. Description of the Related Art
A traditional fan rotor has a magnet and a metal casing attached thereto, which are embedded in a mold of a fan wheel. A hub of the fan wheel encompasses the magnet and the metal casing, and is integrally formed by plastic injection molding. In order to maintain balanced rotation of the fan wheel, the fan wheel, the magnet and the metal casing are formed as a singular member in the manufacturing process. However, in the mold assembly the fan wheel must be injected one at a time. If more than two fan wheels are injected at a time, the temperature in the mold cannot be controlled precisely due to the different temperatures of more than two sets of the magnet and the metal casing prior to being contained in the mold. The different temperatures in the mold result in different molding flow of plastic therein. This causes a fan wheel product mismatch. Consequently, the multi-molding process fails to accomplish the specific balancing rotation of each fan wheel manufactured by a single-molding process. Still, the single-molding process reduces manufacturing efficiency and increases manufacturing cost.
Referring to FIG. 1, a conventional fan wheel includes a rotor 90, a hub 91, and a plurality of resilient members 92. Each end of the resilient members 92 is provided with an engaging hook 93 adapted to engage with a metal casing 94, which is attached to a magnet. The resilient members 92 are integrally formed with the hub 91 so that a great many of the fan wheels may be injected at one time in the molding process. However, the resilient members 92 complicate the entire mold structure of the fan wheel and increase the manufacturing cost of the mold.
The present invention intends to provide a magnet-positioning device for a rotor having assembling members adapted to combine a metal casing with a rotor hub in such a way to mitigate and overcome the above problem.
The primary objective of this invention is to provide a magnet-positioning device for a rotor having assembling members adapted to combine a metal casing with a rotor hub.
The magnet-positioning device for the rotor in accordance with the present invention mainly comprises a rotor hub, a metal casing, and an annular magnet. The rotor hub includes an annular wall and an engaging portion formed thereon. The engaging portion is adapted to engage with the metal casing, which is integrally adhered with the annular magnet. The metal casing includes a first end edge and a second end edge, and an outer diameter formed by the second end edge is slightly greater than an inner diameter formed by the engaging portion.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description and the accompanying drawings.